https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100117
--- Comment #1 from Florian Weimer <fw at gcc dot gnu.org> --- This looks like the old C++ _GNU_SOURCE issue. But I do not really see why <iostream> includes <csignal>. Is this some PCH test? Should <stdc++.h> really include all the C headers?
